Re: arrangemnt of my coil

From: 	Julian Green[SMTP:julian-at-kbss.bt.co.uk]
Sent: 	Monday, July 28, 1997 10:30 AM
To: 	tesla-at-pupman-dot-com
Subject: 	Re: arrangemnt of my coil

>how does a choke work? how does it protect the transformer? how about
>using a sparkgap, would that take place of a choke or should they both
>be used?

Chokes act like shock absorbers and protect the HV windings of the transformer
from the RF generated in the tesla primary tank circuit.  This RF can easilly
cook the insulation of the transformer which results in breakdown.

A choke works by having a high resistance/impedance to rapidly changing voltage
but has a low resistance to DC.   This allows the relativly slowly changing AC
from your transformer to pass through, but acts as a block to high frequency 
AC.  (all due to self induced voltage)

I wind my chokes on plasic tube single layer (like small TC secondary) and 
these perform very well.  I must admit I have tried and failed using toroids
chokes, I could not stop the arcing between turns (toroid chokes use fewer turns
thus more volts per turn).

Yes you should use a spark gap on the transformer outputs to protect against
any RF that gets through.   You set the gap to be just large enough to 
prevent arcing when full output voltage is present but no TC in operation.

Julian Green